1. Field of the Invention
The present invention relates generally to disk drives, and more particularly to a disk drive having a damping member for damping disk movement with respect to a spindle motor hub.
2. Description of the Prior Art
The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the HDA. The head disk assembly includes at least one magnetic disk, a spindle motor for rotating the disk, and a head stack assembly (HSA) having an actuator assembly having at least one transducer head, typically several, for reading and writing data to and from the disk. The printed circuit board assembly includes a servo control system in the form of a disk controller for generating servo control signals. The head stack assembly is controllably positioned in response to the generated servo control signals from the disk controller. In so doing, the attached heads are moved relative to tracks disposed upon the disk.
The head stack assembly includes an actuator assembly, at least one head gimbal assembly, and a flex circuit cable assembly. A conventional “rotary” or “swing-type” actuator assembly typically comprises an actuator body that rotates on a pivot assembly between limited positions, a coil portion that extends from one side of the actuator body to interact with one or more permanent magnets to form a voice coil motor, and one or more actuator arms that extend from an opposite side of the actuator body. A head gimbal assembly includes at least one transducer head, sometimes two, which is distally attached to each of the actuator arms. The actuator assembly includes the actuator body that has a bore and a pivot bearing cartridge engaged within the bore. The head gimbal assembly and the flex circuit cable assembly are attached to the actuator assembly.
The spindle motor includes a spindle motor hub that is rotatably attached to the disk drive base. The hub has an outer hub flange that supports a lowermost one of the disks. Additional disks may be stacked and separated with annular disk spacers that are disposed about the hub. A disk clamp is provided which is attached to an upper end of the hub in mechanical communication with an uppermost one of the disks for applying a clamping force to the disk towards the hub flange.
The spindle motor further includes an annular magnet element and a spindle motor stator. The magnet element is typically attached about the hub below the hub flange. The magnet element consists of a predetermined number of N and S poles that are disposed alternately circumferentially about the magnet element. The stator includes an outer stator rim that is attached to the disk drive base and a plurality of stator teeth. The stator is sized to fit about the hub and in particular the magnet element. Each stator tooth includes windings that selectively conduct current to create a magnetic field that interacts with the various poles of the magnet element. Such interaction results in forces applied to the hub which tend to rotate the hub.
A topic of concern is the desire to reduce vibrations or vertical movement of the disks during operation of the disk drive. Such movement may be a result of airflow generated within the disk drive due to rotation of the disks for example. In particular, such disk rotation induced airflow may result in various modes of vibration of the disks, i.e., disk flutter. This results in an increase in the percent off-track values of the associated heads attempting to read/write data to and from such vibrating disks. Accordingly, there is a need in the art for an improved disk drive for mitigation of the effects of vibration of the disks in comparison to the prior art.